Revert of Relanding "Fixed title updating for back forward navigation."

ios/chrome/browser/tabs/tab.mm

Index: ios/chrome/browser/tabs/tab.mm
diff --git a/ios/chrome/browser/tabs/tab.mm b/ios/chrome/browser/tabs/tab.mm
index 7dd1d6e65ed22f3cb52906c3083549605fd230e9..9c5817c93f2cc87c952e47199a85086a156df635 100644
--- a/ios/chrome/browser/tabs/tab.mm
+++ b/ios/chrome/browser/tabs/tab.mm
@@ -337,6 +337,10 @@
 // Sets the favicon on the current NavigationItem.
 - (void)setFavicon:(const gfx::Image*)image;
 
+// Updates the title field of the current session entry. Also updates the
+// history database.
+- (void)updateTitle:(NSString*)title;
+
 // Saves the current title to the history database.
 - (void)saveTitleToHistoryDB;
 
@@ -987,6 +991,20 @@
       setDelegate:overscrollActionsControllerDelegate];
   overscrollActionsControllerDelegate_.reset(
       overscrollActionsControllerDelegate);
+}
+
+- (void)updateTitle:(NSString*)title {
+  web::NavigationItem* item = [self navigationManager]->GetVisibleItem();
+  if (!item)
+    return;
+  item->SetTitle(base::SysNSStringToUTF16(title));
+  // TODO(crbug.com/546218): See if this can be removed; it's not clear that
+  // other platforms send this (tab sync triggers need to be compared against
+  // upstream).
+  if (webStateImpl_)
+    webStateImpl_->GetNavigationManagerImpl().OnNavigationItemChanged();
+
+  [self saveTitleToHistoryDB];
 }
 
 - (void)saveTitleToHistoryDB {
@@ -1813,8 +1831,13 @@
 
 - (void)webController:(CRWWebController*)webController
        titleDidChange:(NSString*)title {
-  [self saveTitleToHistoryDB];
-  [parentTabModel_ notifyTabChanged:self];
+  NSString* oldTitle = [self title];
+  BOOL isTitleChanged = (!oldTitle && title) || (oldTitle && !title) ||
+                        (![oldTitle isEqualToString:title]);
+  if (isTitleChanged) {
+    [self updateTitle:title];
+    [parentTabModel_ notifyTabChanged:self];
+  }
 }
 
 - (BOOL)urlTriggersNativeAppLaunch:(const GURL&)url